/*
* TLS Record Handling
* (C) 2004-2012 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#ifndef BOTAN_TLS_RECORDS_H__
#define BOTAN_TLS_RECORDS_H__

#include <botan/tls_magic.h>
#include <botan/tls_version.h>
#include <botan/aead.h>
#include <botan/block_cipher.h>
#include <botan/mac.h>
#include <vector>
#include <chrono>

namespace Botan {

namespace TLS {

class Ciphersuite;
class Session_Keys;

class Connection_Sequence_Numbers;

/**
* TLS Cipher State
*/
class Connection_Cipher_State
   {
   public:
      /**
      * Initialize a new cipher state
      */
      Connection_Cipher_State(Protocol_Version version,
                              Connection_Side which_side,
                              bool is_our_side,
                              const Ciphersuite& suite,
                              const Session_Keys& keys);

      AEAD_Mode* aead() { return m_aead.get(); }

      const secure_vector<byte>& aead_nonce(u64bit seq);

      const secure_vector<byte>& aead_nonce(const byte record[], size_t record_len, u64bit seq);

      const secure_vector<byte>& format_ad(u64bit seq, byte type,
                                           Protocol_Version version,
                                           u16bit ptext_length);

      BlockCipher* block_cipher() { return m_block_cipher.get(); }

      MessageAuthenticationCode* mac() { return m_mac.get(); }

      secure_vector<byte>& cbc_state() { return m_block_cipher_cbc_state; }

      size_t block_size() const { return m_block_size; }

      size_t mac_size() const { return m_mac->output_length(); }

      size_t iv_size() const { return m_iv_size; }

      size_t nonce_bytes_from_record() const { return m_nonce_bytes_from_record; }

      size_t nonce_bytes_from_handshake() const { return m_nonce_bytes_from_handshake; }

      bool cbc_without_explicit_iv() const
         { return (m_block_size > 0) && (m_iv_size == 0); }

      std::chrono::seconds age() const
         {
         return std::chrono::duration_cast<std::chrono::seconds>(
            std::chrono::system_clock::now() - m_start_time);
         }

   private:
      std::chrono::system_clock::time_point m_start_time;
      std::unique_ptr<BlockCipher> m_block_cipher;
      secure_vector<byte> m_block_cipher_cbc_state;
      std::unique_ptr<MessageAuthenticationCode> m_mac;

      std::unique_ptr<AEAD_Mode> m_aead;
      secure_vector<byte> m_nonce, m_ad;

      size_t m_block_size = 0;
      size_t m_nonce_bytes_from_handshake;
      size_t m_nonce_bytes_from_record;
      size_t m_iv_size = 0;
   };

/**
* Create a TLS record
* @param write_buffer the output record is placed here
* @param msg_type is the type of the message (handshake, alert, ...)
* @param msg is the plaintext message
* @param msg_length is the length of msg
* @param msg_sequence is the sequence number
* @param version is the protocol version
* @param cipherstate is the writing cipher state
* @param rng is a random number generator
* @return number of bytes written to write_buffer
*/
void write_record(secure_vector<byte>& write_buffer,
                  byte msg_type, const byte msg[], size_t msg_length,
                  Protocol_Version version,
                  u64bit msg_sequence,
                  Connection_Cipher_State* cipherstate,
                  RandomNumberGenerator& rng);

// epoch -> cipher state
typedef std::function<std::shared_ptr<Connection_Cipher_State> (u16bit)> get_cipherstate_fn;

/**
* Decode a TLS record
* @return zero if full message, else number of bytes still needed
*/
size_t read_record(secure_vector<byte>& read_buffer,
                   const byte input[],
                   size_t input_length,
                   bool is_datagram,
                   size_t& input_consumed,
                   secure_vector<byte>& record,
                   u64bit* record_sequence,
                   Protocol_Version* record_version,
                   Record_Type* record_type,
                   Connection_Sequence_Numbers* sequence_numbers,
                   get_cipherstate_fn get_cipherstate);

}

}

#endif